By now, it’s pretty much indisputable among health-care designers that hospitals must fold nature into the patient experience. At Stanford, our work for the new Lucile Packard Children’s Hospital makes natural elements obligatory. All patient-room windows have planter boxes, for instance, and patients can take in Palo Alto’s rolling foothills from outdoor decks. Also, there’s an enormous backyard garden with great thickets of lavender and truly world-class play structures. Inside and out, much of the wayfinding is based on local plants and animals. It’s all very relaxing.

“We know in our hearts that people feel better when they’re relaxed and nature is nearby,” says Robin Guenther, a global practice leader for Perkins+Will. “So at Lucile Packard, we asked ourselves what we could do to bring nature and healing into a closer relationship.” But how can we empirically say that nature has any impact all? Beyond the anecdotal, what evidence is there? What is nature even doing when we say it’s “helping”?

Amid all that goes into healing, isolating nature as a factor can be a little challenging. Two complementary schools of thought prevail, one citing stress relief, the other looking at how we pay attention.

One study, published in Science in 1984, set the precedent for similar findings to come by identifying stress as the biggest hindrance to recovery. Roger Ulrich, an environmental psychologist, looked at 46 patients who had each undergone gallbladder surgery and spent seven days recovering at a hospital in suburban Pennsylvania. Of those patients, half were in rooms with windows that looked onto leafy trees; the other half got to look at a brick wall. The first group had shorter recovery times, used significantly less pain medication, saw fewer post-surgical complications and complained less.

Over the years since, Ulrich has developed stress reduction theory (SRT) to explain emotional and physiological reactions to natural spaces. We see natural elements, and a positive response arises. We want to get closer and relax amid sustained, wakeful attention. Stress melts away, and recovery follows that much more easily.

There’s no question that relaxation is one of several portals to better care. “Even if nature itself is one factor of many in relaxation, it can act as a ‘shortcut’ to all the clinical goodies that come with lowering stress, from the heart rate and immune system outward,” Guenther says. “And in the context of healthcare, that shortcut can be crucial.”

Just as Ulrich’s work led to SRT, two environmental psychologists at the University of Michigan, Rachel and Stephen Kaplan, have steadily developed like-minded research on what they call attention restoration theory (ART). In activities demanding prolonged, effortful focus, our capacity for mental attention steadily depletes, leading to fatigue, frustration, and inability to concentrate. But, as Stephen wrote in a seminal 1995 paper, there is an antidote. “Natural environments turn out to be particularly rich in the characteristics necessary for restorative experiences.”

Kaplan wasn’t addressing healthcare setting specifically, but the takeaway was clear. Nature attracts our attention through a “soft fascination,” permitting low-effort recovery from mental fatigue. His 1995 paper, which sought to bridge SRT and ART, identified four restorative qualities worth emphasizing: “the environment must have sufficient extent, the environment must be compatible with one’s goals, the environment must give people the sense of being away, and the environment must be fascinating.” (These actually constitute a pretty great design concept for a hospital.)

While this realm is still accumulating data and exploring the implications, architecture has been slow to translate findings into clinical environments. As Guenther points out, “Ulrich’s groundbreaking work is more than 30 years old, but the US still produces hospital environments where caregivers never see daylight or views, all in the name of minimizing travel distance.”

Not at Packard. Because we now understand just how exquisitely attuned humans can be to subtle hints of nature, our designers sought to minimize hospital-ness wherever possible, from sounds to smells to everything else. We know that a straight line and a pleasantly curvy one register differently in patients. We know that patients will recover quicker when they’ve watched hummingbirds buzz around a fragrant garden.

Armed with such findings, we can now tap into a range of ideas that draw on nature’s immediate vitality. In a setting where recovery is paramount, the natural elements of recovery are now more crucial than ever. And that’s one of the best outcomes we could ask for.